iMac 5k and using a second monitor with it - resolution and cable

Question

Level 1

8 points

iMac 5k and using a second monitor with it - resolution and cable

As a main computer, could I use an iMac 5k 2019 at full 5k resolution, and then as a second monitor, use a Apple iMac 24-Inch "Core 2 Duo" 2.66 (Early 2009) with an active matrix display with a native resolution of 1920x1200?

Details and specs:

Apple iMac 27-Inch "Core i5" 3.1 (5K, 2019) with 16:9 widescreen TFT active matrix "Retina 5K" display with a native resolution of 5120x2880. USB-C/Thunderbolt 3 port. OSX 10.14 thus not supporting Target Display Mode.

I want to use my Apple iMac 24-Inch "Core 2 Duo" 2.66 (Early 2009) with an active matrix display with a native resolution of 1920x1200 as a second monitor. It has a mini display port

The iMac 2019 documentation says: This model can simultaneously support the internal display at full native resolution and up to one 5120x2880 (5K) external display at 60 Hz with support for one billion colors; two 3840x2160 (4K UHD) external displays at 60 Hz with support for one billion colors; or two 4096x2304 (4K) external displays at 60 Hz with support for millions of colors. It supports both extended desktop (second workspace) and video mirroring (internal display duplicated on the external display) modes.

Cable

I am using a Unidirectional USB C to Mini DisplayPort Cable (USB C to Mini DP Cable) Supporting 4K 60Hz manufactured by Cable Matters.

Saying explicitly: "USBC to Mini DisplayPort adapter cable is Not compatible with Thunderbolt/Thunderbolt 2 port. Mini Displayport to USB C cable is not compatible with old MacBook, MacBook Air, MacBook Pro, Mac Pro, or iMac with Thunderbolt/Thunderbolt 2. USB-C to Mini DisplayPort adapter cable is not compatible with audio interface or hard drives with Thunderbolt/Thunderbolt 2. Does not support Target Display Mode or Target Disk Mode. "

There is not image on the iMac 2009.

My questions:

Can I use the 2009 iMac with lower resolution as a secondary display?

Am I using the right cable?

What steps do I take next to make it work?

Posted on Apr 4, 2020 8:14 AM

Reply

Answer 1

rkaufmann87

Level 10

148,386 points

Apr 4, 2020 9:02 AM in response to MarkJB99

In short it will not work, Target Display Mode only worked well some iMacs. Your early 2009 and Retina display were never able to do Target Display Mode. In short, you are wasting your time. We get your question on average 3-5 times a day and the answers are always the same. If you need an external display for the Retina, then buy one the early 2009 will NOT work.

Use your iMac as a display with Target Display Mode

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Answer 2

BDAqua

Level 10

250,247 points

Apr 4, 2020 8:46 AM in response to MarkJB99

You could use a lower Resolution, but...

Note: Target Display Mode isn’t supported on iMac models with Retina display. Only iMac (27-inch, Late 2009), iMac (27-inch, Mid 2010), and iMac (Mid 2011 to Mid 2014) support Target Display Mode.

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Answer 3

MarkJB99 Author

Level 1

8 points

Apr 4, 2020 8:53 AM in response to BDAqua

Hi BDAqua,

Thank you for your swift reply.

However, I am not sure if I get it: maybe the full response did not come through as it says:

"You could use a lower Resolution, but...

Note: Target Display Mode isn’t supported on iMac models with Retina display. Only iMac (27-inch, Late 2009), iMac (27-inch, Mid 2010), and iMac (Mid 2011 to Mid 2014) support Target Display Mode."

Please advise,your response so far makes me curious.

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